dssim-3.2.3-bp156.2.8

- Update license based on the recent legaldb review

- update to 3.2.3:
  * 25% faster
  * WASM compatibility
  * use more accurate pooling algorithm
  * rewrite in Rust
  * Chroma channels are compared at full resolution.
  * This increases accuracy on images with chroma subsampling.
  * All scaling is done in linear-light premultiplied-alpha color
    space, which further increases accuracy.
  * Safe and reliable code. No more dodgy pointer manipulatio n
  * Fixed handling of PNG files with invalid chunks
  * Fixed handling of color channels smaller than 8 pixels

- initial package, version 1.3.2